1. Field of the Invention
The present invention relates to a light-emitting device.
2. Description of Related Art
In recent years, as for lighting fixtures for general lighting, the utilization of light-emitting diodes (hereinafter may be referred to as “LED”) of lower power consumption has been developing, in place of conventional incandescent bulbs, and the fields of its application have been expanding into various fields, which are exemplified by uses of backlights, lighting, and vehicles. In particular, LEDs in which nitride based semiconductors are used have a wide band gap and can emit light of which the wavelength is short, so that the utilization of the LEDs has been developing in recent years.
The aforementioned light-emitting devices generally have a structure in which a light-emitting element such as an LED is mounted in a cavity of a package, which may be made of a resin material, so as to extract light to the outside. In such a structure, in order to improve its light extraction efficiency, a coating of a metal may be applied in the cavity of the package made of a resin material to increase the reflectance. For a metal material, metal having high reflectance, for example, Ag is used.
On the other hand, Ag may be discolored due to sulfurization, which may result in a decrease in the reflectivity, which may lead to the use of a dielectric multilayer film (e.g., distributed Bragg reflector: DBR) for the coating in the cavity in place of such a metal film (e.g., Japanese Unexamined Patent Application Publication No. 2008-300621).